In a perfect world we would all eat 100% live food all of the time. Everything would be raw and free from bacteria that make us sick. Fruits and veggies would be abundant every season of the year and wild game (that isn't feeding of off GMO crops) would be right outside of our back door for us to consume whenever we need it.
Obviously, we do not live in a perfect world. Food-borne illness exists. Seasons change, making it impossible to grow fruits and veggies at times. Modernization and industrialization have changed our environment and the way we have to grow and preserve food.
Our ancestors had many different ways to deal with these problems. Some of them were nomadic and moved with the changing seasons so that fresh fruits and veggies would always be available no matter where they were. Others stayed put through the harsh winters and relied on traditional methods of preserving food in order to survive through "hibernation". Most of them, though, resigned to only eating what is in-season and available locally for them. If that means you only ate apples in the fall or berries in the spring, that's the way it had to be.
Thankfully, through time, new methods of food preservation have evolved and we're not forced to let the season determine our menus. While the tried and true methods of lacto-fermentation, smoking, and drying food will always be best, they are not always convenient or possible for everyone. Freezers and canning methods are the solution for those people. Some will look at these methods of preservation and say that because they are new and not what our ancestors used they are unhealthy, un"primal", or "processed", but I argue that just because it's new, it doesn't necessarily mean it's bad or evil. Not everything that is "processed" is the equivalent of a Twinkie, and in fact, the processing can make some foods even healthier for us to digest.
Why Preserve Food?
Environmental responsibility is just as important as the food we put into our bodies, mainly because it affects what we put into our bodies in the long-run. Because there are changing seasons, many areas of the world are unable to grow fresh produce for a large part of the year. In order to get their required nutrition, people living in these areas need to either preserve foods when they are in season or have fresh foods shipped to them from other parts of the world when they are out of season. Preserving the food while in season so it can be eaten throughout the year is the more environmentally responsible option. On top of that, it is better for your local economy, as you're supporting local farmers during their growing seasons by buying their products in bulk instead of supporting farmers overseas throughout the rest of the year.
Frozen or Canned
There are many people who are very anti-canned foods, because they feel canning leaves the food dead and denatured. These people will, however, rely on freezers to preserve their foods. While canning does create a sterile, dead food (void of both bad AND good bacteria), it does not mean the food is entirely denatured. My purpose in this post is to show you how and why.
I would also argue that while freezing is a wonderful method of preservation, it also, technically, creates processed food, and simply isn't practical for the average family to practice for ALL foods. In my family of six, it can take hundreds of quarts of canned applesauce from apple season in order to provide enough for us to eat just 2-3 times a week during the off-season. Just the applesauce alone would require an entire chest freezer for preservation. If you're a family that also buys your local, pastured meat in bulk, preserves many different varieties of foods other than applesauce, or perhaps has a breastfeeding infant that requires pumped milk, freezer space is precious and not readily available for bulk food preservation. A solution could be to buy multiple freezers, but once again, environmental responsibility is just as important as the food we consume. Freezers use a lot of energy.
While canning does create a sterile, dead food (void of living bacteria - both good and bad), it does not mean the food is entirely denatured. We have to make choices about how we preserve food based on the amount of space we have, what the heating process does to the specific food, and what is best for the environment.
What does the canning process do to the nutrients in food?
Studies have shown that there are both good and bad things that happen to the nutrients in foods that are canned. Vitamin C is lost during the canning process, but what little remains afterwards is stable throughout storage. The same for many of the B Vitamins. During the freezing process, on the other hand, very little of these nutrients are lost during blanching, but they are not stable during storage due to oxidation. Frozen produce consumed within a month is going to be more nutritious than if it was stored in the freezer for six months, whereas the nutrients in canned foods will remain stable throughout the shelf-life of the food. So a year after preservation, the canned food will usually be more nutrient dense than the frozen food, depending on moisture levels and the temperature of the freezer, of course.
On the other hand, the canning process opens up the cell walls of fruit flesh, making things like Vitamin A and carotenes more readily available. Very few of these nutrients are lost during the canning process, and in the case of things like tomatoes, the carotenes, like lycopene, will actually increase. Freezing produce, however, does not cause an increase in nutrients, with the exception of things like peaches where freezing yields 21 times more Vitamin C than fresh (canning yields only four times more than fresh - but the canned peaches have more Vitamin E than both frozen and fresh).
Fiber is another thing to consider when canning. The high heat does not affect fiber content, but rather makes it more soluble and useful to the body. Freezing does not do this.
The bottom line is this - both methods of preservation have their pros and cons. Canning creates a sterile, dead food that in some cases can be lower in nutrients, but it allows for more convenient storage and does not cause long-term nutrient loss. Freezing means less nutrient loss up front and leaves both good and bad bacteria intact, however it allows for more nutrient loss during the storage process due to oxidation. It also takes up more room in your freezer, and preservation of the food is dependent on access to electricity. If you've ever had a full freezer during a long-term power outage or have had a freezer door accidentally left open (like me), then you understand how inconvenient and costly this problem can be!
When to Can and When to Freeze?
Bone Broth
I've posted before about how I can my bone broths. There are many who think this is an unwise thing to do, as the high heat of the canning process can affect your gelatin. This is true - not all canned broth will gel afterwards. But, that doesn't mean that there is no benefit to canned broth.
When buying processed gelatin in the store, you can usually find two types - regular gelatin powder and collagen/gelatin hydrolysate. Gelatin powder is like the equivalent of uncanned bone broth reduced to a powder. It will gel and create things like gummy snacks. Collagen hydrolysate is like the equivalent of canned broth. It is heated at a higher temperature than regular gelatin powder, which increases the number of amino acids. While collagen hydrolysate will not gel, much like canned broth, it is better assimilated into the body. Collagen hydrolysate is actually better for people like me, with Crohn's Disease, as it is easier on digestion.
I see benefit to both freezing and canning bone broth. It is good to have some fresh off the stove or crockpot, some kept in your fridge for quick use, and some in either the freezer or canned for those times when you need it and don't have it fresh. Canned broth, since already heated, is perfect for things like soups and stews. Frozen is good for thawing and warming as a beverage.
Meat
Canning meat is one of the easiest things in the world to do. You simply take the raw meat, chop it into little pieces, fill the jar with water, and process in the pressure canner. When you are done you have a preserved jar of canned, pastured meat for those days when you may not have had time to thaw your meat before cooking or you need to take a meal with you somewhere.
Meat, unless you're eating it raw, is going to lose nutrition through preparation regardless of the method. Canning the meat brings it to a temperature of 240 degrees for a few hours and then allows all nutrients to remain stable throughout storage. You may end up cooking fresh or frozen meat at the same or higher temperature, losing the same nutrients. Canning will render the meat sterile, whereas cooked meat can quickly lead to food-borne illness if not handled and preserved properly after it is taken off of the heat.
For some meats, such as fish, the canning process will actually increase nutrition. The high heat causes bones in fish meat to leach calcium into the meat.
Vegetables
Let's face it, canned veggies often don't taste as good as fresh or frozen. Green beans, for example, can end up mushy. And the longer the jars sit in storage, the worse the flavor seems to be.
But some veggies, like leafy greens, actually benefit from the heat. Spinach that sits in your fridge can lose nearly all of its nutrient content in one week (that doesn't count the 2-3 weeks it can take for it to get to your fridge from the farm during winter). Cooked spinach increases iron, protein, fiber, zinc, thiamine, and calcium; and has higher amounts of vitamins A and E. Spinach that is picked ripe and canned immediately will have much more nutrition than store-bought spinach that you bring home and immediately use up, and way more than spinach that sits in your fridge for a week longer.
With any veggies, if you're worried about nutrient loss during the canning process, remember that most of what is lost ends up in the cooking liquid. Since canned veggies are only really good in cooked foods like stews or soups, it is best to use the liquid from your jars in the soups in order to increase nutrition and make up for what was lost in the veggie itself.
A 2005 Dutch study suggested that canning fruits and vegetables decreases glucosinolate content - a phytochemical that may fight cancer and memory loss. Glucosinolates are primarily found in cruciferous veggies like cabbage or broccoli. Since broccoli is high in Vitamin C, it is not recommended that you can for preservation. And cabbage is best preserved through lacto-fermentation as sauerkraut. To benefit from the protection of glucosinolates, just preserve the foods high in them with other methods and serve them as a side with your home-canned foods that lack them.
Fruits
As is the case with broccoli, it is best not to can fruits that are high in Vitamin C.
Some people have luck canning pumpkin, although I have never tried. Canned pumpkin has 30 times more vitamin A than raw pumpkin and 20 times more than fresh-cooked.
Other fruits, such as apples, provide fiber as their benefit. Since the canning process does not affect fiber, and actually enables better digestion, apples are one fruit that is best preserved through canning. You could argue that it would be best to freeze applesauce, as not to make it a dead food, but the heating process used to create the applesauce itself has already rendered it dead. Freezing will not make it live again. Canning will free up freezer space for items that cannot be preserved through canning, such as squash and citrus fruit, and allow you to buy apples in bulk during the growing season.
Fruits such as berries are best when frozen if you're looking to consume them for nutrition, but since they aren't a main source of vitamin C to begin with, canning will not make much of a difference. It is nice to have some frozen berries to enjoy in things like smoothies for a nutrient punch, with some canned berry jams in the cupboards to use as condiments and for flavor.
As mentioned above, always can your tomatoes instead of freezing, as the process increases the amount of lycopene in the fruit.
Conclusion
All food methods have benefits. When you're looking at 15 bushels of fresh apples, it would be impossible to freeze it all. Dehydrate some into chips. Freeze some for baking. Can some applesauce.
When you get your full beef you can dehydrate or smoke some for jerky. Can some for a convenient meal later. Freeze the rest to enjoy throughout the year.
Unfortunately, we can't always forage and hunt for the freshest of foods. We have to make sacrifices in order to be able to live in the modern world. Raw, live foods are rare and when they are plentiful, they are rarely safe when eaten raw. Even most of the "raw" almonds you find in the store are irradiated and left dead. It's the unfortunate consequence of desiring almonds when you don't live in almond country. In order for to food to get to our doors year-round, whenever we're craving them, they have to be made safe for transport. The same will be true when you're desiring berries in the winter or bananas in the North.
Don't let your fear of eating "dead" foods (in moderation) keep you from enjoying the art of canning your own delicious foods. Yes, a raw egg is best for you nutritionally, but you will still eat it when it is cooked and dead, won't you? Just because a food is canned, it doesn't mean it's not good for you.
As with any meal, it's always good to eat more live than dead foods and no one is advocating a diet consisting solely of home-canned foods. If you decide to have some of your canned applesauce with a meal, make sure that you add some homemade yogurt or large portions of raw veggies to the meal. If you're eating canned meat, top it with a fermented cruciferous veggie, like homemade sauerkraut. If you're enjoying some of your homemade unsweetened berry jam with a meal, add raw, local honey to it before serving to "liven" it up. Balancing dead foods with live ones will create a healthy, nutritious meal that is also environmentally-friendly and supports local farmers year-round.
A jar of in-season, home-canned produce is going to be more nutritious than out of season produce at the grocery store, and also better for the environment. Period. You also can't downplay the security in knowing that the organic, local food you worked so hard to preserve will be stable regardless of whatever happens to the power.
Finally, remember that whenever you're canning, always use proper sanitation and hygiene guidelines. Use lids that are free of BPA and other toxins, and always make sure to dispose of any jars that show signs of seepage or spoilage.
-Jessica
Sources
http://ucce.ucdavis.edu/files/datastore/234-779.pdf
http://nutrican.fshn.uiuc.edu/studyfinal.html
